933102018-01-1025x Space Fresnel Lens Concentrator Using 4(+) Junction IMM Solar Cells and Nyctinastic Graphene Radiators to Mitigate LILT Effects for Outer Planet Missions, Phase IActiveJun 2017Jun 2018The innovation is a unique solar array for powering NASA's deep space missions without the low-intensity, low-temperature (LILT) problems of conventional arrays. The new array uses a robust, ultra-light, color-mixing Fresnel lens to point-focus sunlight at a 25X concentration ratio onto the most advanced 4-junction and 6-junction inverted metamorphic (IMM) photovoltaic cells. Waste heat from the cells is dissipated to space by a bio-inspired nyctinastic graphene radiator. The radiator passively folds up around the cell, like a flower at night, to reduce the drastic temperature drop in deep space, due to the reduction in solar irradiance at large distances from the sun. The 25X concentration and the high-optical-efficiency lens eliminate the low-intensity (LI) problem by maintaining an irradiance on the cell of nearly one AM0 sun at 5 AU distance from the sun. The nyctinastic radiator mitigates the low-temperature (LT) problem of conventional arrays by maintaining the cell temperature at about -100 C instead of the typical -140 C at 5 AU. This warmer cell temperature minimizes changes in band gaps for the 4 junctions or 6 junctions in the cell, thereby maintaining better current matching for the series-connected junctions. The performance metrics of the new array are unprecedented. The expensive solar cells are reduced in area and cost by 95% compared to conventional one-sun cells. The cells can be heavily shielded front and back from space radiation at very low mass penalty, due to the small cell size. The overall specific power of the lens + cell assembly + radiator is more than 1,400 W/kg for a heavily shielded cell, about 3X better than for a one-sun cell with the same shielding. The feasibility of the new array technology will be proven in Phase I by the small business (Mark O'Neill, LLC), the research institution (University of Connecticut), and the IMM cell firm (SolAero). In Phase II, fully functional hardware will be developed and delivered.The new array will apply to a wide range of NASA missions, most of which use solar power. The new array's superior attributes include LILT-mitigation, scalability to high power, radiation hardness at low mass penalty, reliable high-voltage operation, outstanding power metrics (specific power, areal power density, and stowed power volume), and low cost per Watt. The LILT mitigation will be ideal for deep space missions to the outer planets and their moons. These other attributes will be especially important for high-power missions of all types, including Solar Electric Propulsion (SEP) missions. The high unit cost (e.g., >$10/sq.cm.) of advanced multi-junction solar cells (e.g., IMM cells), may make conventional one-sun solar arrays too expensive for very high-power NASA missions, such as, for example, 300-600 kW SEP tugs to carry large amounts of cargo from low earth orbit (LEO) to GEO, the Earth-Moon Lagrange Points, lunar orbit, Mars orbit, or beyond. For such high-power missions, the new array could be mission-enabling because of its much lower cost per Watt, combined with its superior performance attributes, compared to one-sun arrays. The new array is also high-temperature-capable, allowing inner planet missions or slingshot trajectories to the outer planets. Potential NASA customers of the new array therefore include the Space Technology Directorate, the Science Directorate, and the Human Exploration and Operations Directorate.<br /><br />The new array will apply to a wide range of non-NASA space missions, most of which use solar power. The new array's superior attributes include specific power (W/kg), stowed power density (kW/cu.m.), areal power density (W/sq.m.), high-voltage operation, radiation hardness, and low cost per Watt, all critical to non-NASA customers including established space companies (e.g., Boeing, Lockheed-Martin, Space Systems Loral, Orbital-ATK, et al.), the U.S. DOD (USAF, MDA, et al.), and newer entries into the space business (e.g., Planetary Resources, Bigelow, Ad Astra Rocket Company, SpaceX, et al.). The U.S. DOD is particularly interested in rad-hard arrays, which led them to fund the SCARLET array that flew on Deep Space 1 in 1998-2001 and the Stretched Lens Array Technology Experiment (SLATE) which flew on TacSat 4. The new array will offer excellent rad-hardness as well as hardness against other potential threats (e.g., ground-based lasers). The new array will also be ideally suited to Solar Electric Propulsion (SEP) missions, including orbit-raising (e.g., LEO-to-GEO for communication satellites), asteroid mining (as planned by Planetary Resources), drag compensation (for inflated space stations in LEO as planned by Bigelow), and multi-hundred-kW spacecraft (as planned by Ad Astra). Our team (Mark O'Neill, LLC, University of Connecticut, and SolAero) is ready to address these applications.22332383Space Power and Energy Storage32553.1Power Generation34393.1.3SolarOthers Inside the Solar SystemSBIR/STTRSpace Technology Mission DirectorateGlenn Research CenterGRCNASA CenterClevelandOHThe University of ConnecticutAcademicStorrsCTConnecticutTexasTherese GriebelCarlos TorrezMark O'neill41785Briefing ChartDocument25x Space Fresnel Lens Concentrator Using 4(+) Junction IMM Solar Cells and Nyctinastic Graphene Radiators to Mitigate LILT Effects for Outer Planet Missions, Phase I Briefing Chart31566https://techport.nasa.gov/file/3156619619940451Briefing Chart ImageImage25x Space Fresnel Lens Concentrator Using 4(+) Junction IMM Solar Cells and Nyctinastic Graphene Radiators to Mitigate LILT Effects for Outer Planet Missions, Phase I Briefing Chart Image30228https://techport.nasa.gov/file/30228218834